Gear motor



E. B. LEA'R GEAR MOTOR -'ylay 9, 1933.

Filed Jan. 5, 1951 IN VEN TOR. ll., mir BY /r l Leal'. .fc

Patented May 9, 1933 EARL 1B. IEAIRJ, OF PHILLIPSBURG, N'EVVl JERSEY,AssIGNon 'ro Indumenti-RAND COMPANY, OF J'ER-SIEYv CITY,NEW JERSEY, ACORPORATION OF NE'WJERSE-Y I GEAR Moron Application med Janaary 5, 1931.seriai No. 506,661.,

This invention relates to gear motors, but more particularly to a gea-rmotor that is automatically responsive to an increase in powerrequirements.

The object of the invention is to provide a gear ymotor which willyoperate at a high degree of efficiency from a point of minimum powerrequirementto its maximum capacity.

@ther objects will bein partobvious and in part pointed out hereinafter.i p

The objects above referred to are accomplished by the mechanismshowninthe ac` companying drawing, in-which Figure 1 shows a front elevationof a hoist with the motor attached partly in section.`

Figure 2 is a sectional viewl of Figure 1 taken on the line 2`2 lookingin the direction indicated by the arrows. Y

Referring more particularly tothe drawing a hoist 10, notshown in detailsince it formsl no partV of .the invention, is-provided withy a drum 12operatively -connected through reduction gearing (not shown) `inthe'case 14 toashaft 16. v 1

A casing 18 secured to a frame member 2O of the-,hoist 10 is adapted `tohouse gears 24, 26, 28 and 80 ofv a gear motor 82. AA cover plate 19provides a closure for the 'end ofthe casing 18 and theA casing18,'-plate 19 and member* 20' are held togetherv by bolts 22. Shafts 34,36 and 38 are journaled in the frame 20 and gears 24, 28 and 80 rotateon' the shafts 84 36 and 38, respectively, Gear 26 is keyed to sha-ft 16by means of a key 40. An enlargement 42 on the 'casing 18 is adapted tohouse a valve 44. A valve chamber 46is formed in the enlargement42. The'valve 44 is of thediiferential type having heads`48 and 50 ofwhichthehead 50 is the head of larger diameter and its inner endsurfaceconstitutes an "actuating surface 51 again st which pressure fluid fromsupply constantly acts. The head 50 tits slidably in the valve chamber46 and the head 48 vis adapted to slide in a reduced portion 52 of thevalve chamber. A vent 54 leads from the atmosphere to the reducedbore-52.' In the head 50 a cup-shaped depression 5,6 isformed. Athreadedplug 58 forms a closure for the valve chamber 46. The plug 58 isprovided with a cup-shaped opening 60 and a set screw 62 'passes throughthe head of the plug 58 into the cup 60. A spring 64 iitted in thedepres sion 56 and'acting against the head 66 of the set screw62 opposesmovement of the valve 44 in the direction of the plug 58. A pipe 68Vconducts pressure fluid "to a passage 7 0 and to the actuating surface51 froma source of supply (not shown) .l An annular groove172 formedinthe inner surface o f the valve chamber 46 connects with aV passage74'lead'- ing to an inlet port V76 between the gears 28 and 30. y 1 Y Ai vA valve assembly similar to that described f above is found on theopposite side of the casing 18.'A This valveassembly comprises a valve78 having heads 80" and 82, a'valve chamber 84, a reduced extension 86of the valve'cha-mber, a set screw 90 having a head` 92, a spring 94 andan annular passage 96.',

A passage 98 leading from the annular passage 96 connects with appipe100 which leads on the gear teeth by the pressure fluid.` Por" tions ofthe motive Huid will'of course "be entrapped between the wall of thecasing and each pair 'of gear teeth. This motive fluid to an inlet port102 between the gears 24 and `The operation of the motor is as follows:

will be dischargedto the atmosphere throughV Y ports 104and 106.l Itwill bevobvious that the shaft 16 will be caused to rotate byrotaltionof the gears 26 and 28. Rotation of the shaftwill be carried'tothe drum of the hoist 12 through the reductiongears which are not shown,thereby causing the drum 12 to rotate and the cable 108 to be woundabout the drum 12. Assuming that too great a load is placed on the cable108 the gears 26 and 28` will fail to rotate fast enough and'fluidpressure will build up in the passage andact upon the valve 44 forcingit 'downward against the resistance of the spring 64there-z by openingpassage 7 4 to the source of pressure fluid'. Pressurel fluid will flowthrough the passage 74 and from the port 76 between the gears 28 and 30.The pressure fluid entering the port 76 will act upon the gears 28 and30 causing them to rotate in a counter clock-wise and a clock-wisedirection, respec-V tively.

If the gears 28 and 30 are able to rotate with sufficient rapidity toprevent a building up of pressure in the passage 7 4, the valve 78 willremain in the closed position, as shown in the drawing and conditions ofload on the hoist and pressure fluid supply to the motor will be suchthat the'load is handled efficiently by the motor. If, however, thegears 28 and 30 rotate so slowly that pressure builds up in the passage74 the valve 7 8 will be opened by pressure acting on the head 82 andpressure fluid will enter the annularpassage 96 and be conducted by thepipe 100 to the port 102. Pressure fluid will then act upon gears 24 and26 tending to cause them to rotate in a counter clock-wise and aclock-wise direction, respectively, thus increasing the power ofthegea-r motor by substantially three-fold.

Ports 54 and 55 leading to the bores 52 and 86, respectively, preventthe formation of a vacuum behind the heads 48 and 80 of the valves 44and 78, respectively. Ports and 112 permit the exhaust of pressurefluid'from the valve chambers 46 and 84, respectively, and rthus preventback pressure fromacting on the valves 44 and 78 when anincrease influid pressure tends to open them. The tension on the springs 64 and 94is adjusted by the set screws 62 and, 90, respectively. A

When the gears 24 and 30 are not in use as auxiliary motors they arenecessarily turning with the motor. Unless the inlet side of these gearsis vented, they will act as vacuum'pumps, load the motor, and wastepower either through the increased load or through opening the valveheads which admit pressure fluid to their inlets and cause them to actas auxiliaries.

In order to permit these gears to idle, ports 109 and 111 are providedin the valves 50 and 82 so that when the valves are in closed positionwith respect to their function as fluid supply valves they are inposition to act as vents by connectingthe liuid supply passages toatmosphere. the motor comprising ygears 28 and 30 is ventedthrough'passages 74, 7 6 and 106, valve chamber 46 and vent 110; Theinlet side of the motor, comprised of gears 24 and 26, is vented throughits corresponding passages.

Assuming that the motor must overcome static friction in the bearings ofthe hoist, as in starting, it will be noted that if the load is toogreat for gears 26 and 28, the valve 44 will be opened and pressurefluid delivered to gears The inletv side of Y 28 and 30, therebydoubling the force exerted onthehoist. Should that force be insufficientanother pair of gears will'be automatically supplied with pressurefluid, and so on until the hoist is started. However, once the staticfriction is overcome, the consumption of pressure fluid will beautomatically reduced in accordance with the power required to run thehoist. And thus the objects hereinbefore re ferred to are accomplished.I claim: f

1. A gear motor comprising a casing, a pair of motor gears rotatablymounted therein, a

fluid supply passage thereto and fluid outlet passages therefrom toadmit and discharge pressure fluid for actuating the motor, anadditional gear in the casing entrained with one of said gears androtatable therewith, and means in the casing to automatically admitpressure fluid to the additional gear and thus cause it to coact withsaid motor gears as an auXiliary thereto. s l v 1 2. A gear motorcomprising a casing, a pair of motor gears rotatablymounted therein, afluid supply passage thereto and fluid outlet passages therefromto admitand discharge pressure fluid for actuating the motor,

an additional gear in the casing entrainedA with one of said gears androtatable therewith, a connecting passage from the inlet side of themotor to an opposite' side thereof between one of the firstmentionedgears of said motor and said additional gear,vand means in said passageto automatically admit pressure fluid to the additional gear and thuscause it to coactwith said motor as an auxiliary thereto.

3. A gear motor comprising acasing, a pair of motor gears rotatablymounted therein, a fluid supply passage thereto and fluid'outletpassages therefrom to admit and discharge pressure fluid for actuatingthe motor, anadditional gear in the casing entrained with one of'saidgears and rotatable therewith, a connecting passage vfrom the inlet sideof VVthe motor to an opposite side thereof between one gear of saidmotor and said additional gear, and means including a valve chest and avalve therein to admit pressure fluid through the connecting passage tothe additional gear in one Vposition of the valve, and passages in thevalve chest and valve to communicate the connecting passage with theatmosphere in another position ofthe valve.

4. A gear motor comprising a casing, a pair of motor gears rotatablymounted therein, a fluid supply passage thereto andfluid outlet passagestherefrom to admit and discharge pressure fluid for actuating the motor,an additional gear in the casing entrained with one of said gears androtatable therewith, a connecting passage from the inlet side of themotor to an opposite side thereof between one gear of said motor andsaid additional gear, and a valve in the casing having an actuatingSurface exposed to pressure fluid in the supply passage whereby, upon anincreaseinthevalue of the pressure fluid in the supply passage, thevalve is actuated to admit pressure fluid into the connecting passageand thus cause the additional gear to coact with said motor as anauxiliary thereto.

5. In a gear motor, a casing, a pair of motor gears mounted therein, apressure Huid supply inlet between said gears to deliver actuating fluidthereto, separate exhaust outlets for each gear, an additional gear inthe casing entrained with one of said gears, a connecting passagefromthe inlet side of the motor to an opposite side thereof between onegear of said motor and said additional gear, and a pressure fluidactuated valve subjected to fluid supply and being responsive tofluctuations in the value of the fluid supply to establish and cut-offcommunication between the source of supply and the connecti ing passage.

' 6. In a gear motor of the relay type, a casing containing a primarygear motor having a plurality of gears, and an auxiliary gear entrainedwith one of the gears, a fiuid inlet between the gears of the primarymotor, a second fluid inlet to deliver pressure fluid to the auxiliarygear, a valve chest having a valve chamber and a port and connectingsaid iiuid inlets, avvalve in said valve chest to control communicationbetween the iluid inlets and being responsive to variations of pressurein the fluid supply, a spring to hold the valve in position to blockcommunication between said iiuid inlets when the motor is 0peratingunder light load conditions, said valve having a port to register withthe first mentioned port for opening said second fluid inlet toatmosphere, and an actuating surface on the valve against which pressurefluid acts to open communication between said fluid inlets and to closesaid second fluid inlet to atmosphere when the motor is under increasedload.

In testimony whereof I have signed this specification.

EARL B. LEAR.

